This invention relates generally to a printing press, and more particularly, to a method and apparatus for converting letterpress and dilithographic printing presses to wet and dry offset printing.
As a result of greatly increasing operating costs and advances in print quality, the newspaper industry has been abandoning letterpress and dilitho printing in favor of offset printing. Until recently, newspaper publishers have had little opinion in this change but to abandon their letterpress and dilitho printing presses as they abandoned letterpress and dilitho printing. As a result, the expense of new offset printing presses has stood as an obstacle to the adoption of offset printing, thereby depriving the public and industry of offset printing advantages.
Attention has focused on the conversion of letterpress and dilitho printing presses to offset printing. Advances have been made, but present conversion methods and equipment have required extensive reconstruction of presses, including the scrapping of many press cylinders. Present methods and equipment also fail to achieve high operating efficiency, maintainability, simplicity, dependability and the highest quality printing. An example of a present method and apparatus is provided by U.S. Pat. No. 4,250,809, issued Feb. 17, 1981. In this example, conversion requires the replacement of the plate cylinders and impression cylinders of the press, and the inclusion of a massive auxiliary frame and bulky replacement cylinders. The conversion also requires integration of gear drives for the replacement cylinders into the existing gear train, with a resultant increase in the load on the drive. Conversion takes extensive time, and involves great expense.